Production or treatment of artificial filaments, threads, yarns, ribbons, and the like



Patented Nov. 16, 1937 PATENT OFFICE PRODUCTION OR TREATMENT OF ARTIFI- CIAL FILAMENTS, THREADS, YARNS, RIB- BONS, AND THE LIKE Henry Dreyfus, London, England No Drawing. Application June 17, 1933, Serial No. 676,337. In Great Britain July 19, 1932 10 Claims.

This invention relates to the production or treatment of artificial filaments, threads, yarns, ribbons, foils, films, and the like made of or containing organic derivatives of cellulose, and par- 5 ticularly to improvements in processes in which the materials are treated with solvents or swelling agents. This application is a continuation in part of application Ser. No. 378,684, filed July 16, 1929.

10 The production of artificial filaments and the like containing organic derivatives of cellulose by wet spinning processes, in which the materials are coagulated in the presence of solvents or swelling agents for the cellulose derivative forming the 15 base of the materials, is described in U. S. Patent No. 1,467,493, and in U. S. application S. No. 402,785 filed 26th October, 1929, while this latter specification also describes processes in which wet spun products are treated immediately after cothe cellulose derivatives. It is stated in U. S. application S. No. 402,785 that the best results are obtained with solvents which are less volatile than the non-solvent liquid or diluent which is used inv 80 in other respects, and it is stated that assisting agents, for example acetone, ethyl alcohol, formaldehyde and glycerine, may be employed in the operation. U. S. application S. No. 378,684 filed 16th July, 1929, is concerned with processes in which artificial filaments .and the like are stretched during their travel from one point to another and in this case also assisting agents are employed. Again, U. S. Patent No. 2,047,195, describes the stretching of artificial materials in 46 the finished condition or continuously with their production by dry or semi-dry spinning processes in the presence of organic solvents in relatively high concentration, for example using a 45 to 55% aqueous solution of -diacetone alcohol or an 45 aqueous solution containing 30% diacetone alcohol and 15% acetone. Further, U. S. application S. No. 573,424 filed 6th November, 1931, describes processes. in which artificial filaments and other products are softened by means of solutions of 50 solvents or swelling agents for the cellulose derivative and are subjected to a stretching process in stages, the tension being substantially removed between at least two of the stages of stretching. Examples of suitable softening solutions which 55 are given include a 50% aqueous solution of diagulation with solutions containing solvents foroxane, and 40% aqueous solutions of acetic acid or acetone.

While the use of relatively volatile solvents for the cellulose derivatives in the production of artificial materials by wet spinningprocesses or in the stretching of artificial materials has certain advantages, yet by reason of the fact that the volatile solvent has at the temperature under which the operation is carried out a higher vapour pressure than the non-solvent employed, 10 it may happen that undesired results, such as loss of lustre, are obtained, particularly when the mixture is removed by evaporation. I have now discovered that the use, in the wet spinning of artificial materials from solutions of organic derivatives of cellulose, or in the stretching of such materials, whether obtained by dry or wet spinning processes, of relatively volatile solvents in conjunction with non-solvent media in the presence of solvents, preferably in small proportions, having a lower vapour pressure than that of the nonsolvent under the conditions at which the operation is carried out, yields very satisfactory products.

According to the present invention, therefore, artificial filaments, threads, ribbons and the like containing an organic derivative of cellulose are coagulated or treated with a relatively volatile solvent for the cellulose derivative together with a. non-solvent therefor, in the presence of a relatively small proportion of a solvent (hereinafter called the less volatile solvent) having, under the conditions prevailing during the operation,

' a vapour pressure lower than that of the nonsolvent. It will be understood that the relatively volatile solvent employed in .the coagulating bath according to the present invention is additional to any which is introduced from the spinning solution by the setting of the shaped materials.

As stated above the proportion of the less volatile solvent employed should be relatively small and, in general, the less volatile solvent should be employed in proportions of 1% to 5% up,to about 10% of the total solvent mixture.

In general it is preferable that the less volatile solvent be applied to the materials simultaneously with the relatively volatile solvent and the non-solvent. The invention is not limited to such simultaneous application of the liquids how- 50 .ever, since the less volatile solvent may, if desired, be applied separately, e. g. before the application of the relatively volatile solvent and the non-solvent.

when the process of the present invention is 1 applied to the wet spinning of solutions of organic derivatives of cellulose the less volatile solvent may be present in the spinning solution itself and the relatively volatile solvent in the nonsolvent medium may constitute the coagulating bath. Preferably, however, the less volatile solvent is incorporated in the coagulating bath together with the other constituents. Where the materials are treated after their formation they may be passed through a bath comprising the relatively volatile solvent in the non-solvent medium together with the less volatile solvent, or the less volatile solvent may be applied separately before the application of the relatively volatile solvent in the non-solvent medium. As an alternative to passing the formed materials through a bath, as described above, the formed materials may be sprayed with the liquids or the liquids may be applied to. the materials by means of rollers, wicks or other similar devices.

' When the process of the present invention is applied to the stretching of artificial materials the less volatile solvent may, as stated above, be applied at a stage separate from the application of the relatively volatile solvent, but preferably the solvents are applied simultaneously from a medium containing both substances. The process may be applied to the treatment of artificial ma terials in the form of hanks, cones, cheeses and other packages, as described for example in U. S. Patent No. 1,709,470, or during the travel of the materials from one point to another, as is described in U. S. application S. No. 378,684. Again, the stretching operation may be carried out in stages, as is described in U. S. application S. No. 573,424, and if desired, means for restricting the application of stretch in the softening bath may be adopted, as is described in U. S. application S. No. 672,800 filed May 25, 1933'. It may also be applied to the treatment of yarns and the like in warp formation, as described for example in U. S. application S. No. 602,844 filed 2nd April,

Among suitable volatile solvents for use in accordance with the present invention may be mentioned acetone, acetic acid, ethylene methylene oxide and dioxane, and solvent mixtures, for example mixtures of ethyl 'acetate and ethyl alcohol, of ethyl alcohol and methylene chloride, or of ethyl alcohol and ethylene dichloride, while examples of the less volatile solventswhich. may be, employed are diacetone alcohol, ethyl lactate,

glycol monoor diacetate, methyl glycol mono- Y acetate, oxanones, e. g. 1.4 oxanone, and alky'lated dioxanes. The non-solvent medium employed is preferably aqueous but, if desired, organic liquids, for example benzene or toluene, may be employed.

The action of the solvent upon the cellulose derivatives, whether such solvents are employed in connection with-wet spinning operations or in stretching processes, may be assisted by the use of salts, sugars or other substances which decrease or tend to decrease the solubility of the solvents in the non-solvent medium, as is described in U. S. applications S. Nos. 469,622 filed 21st July, 1930, 636,943 filed 8th October, 1932, and 638,179 filed 17th October, 1932.

The process of the present invention may be applied to the treatment of artificial materials having a base of any organic derivative of cellulose, for example cellulose acetate or other cellulose ester or mixed ester, such as cellulose formate, propionate, butyrate and nitroacetate, methyl, ethyl, butyl, benzyl and other ethers or mixed ethers of cellulose, and cellulose etheresters such as ethyl cellulose acetate and oxyethyl cellulose-acetate.

Whilst the use of the less volatile solvent in conjunction with the relatively volatile solvent and non-solvent has been described more particularly in connection with the production of artificial materials by the wet-spinning process, and the stretching of artificial materials prepared by either the dry or wet spinning processes, it is to be understood that the invention is not limited to these applications and, in general, such less volatile solvents may be employed in any process in which a relatively volatile solvent, and a nonsolvent are applied to the artificial materials.

The following examples are given in order to illustrate the invention but it is to be clearly understood that they do not limit it in any way:

Earample 1 A 25% solution of cellulose acetate in acetone is extruded through nozzles having jet orifices of .08 mm. diameter into a coagulating bath containing 40-45% dioxane, 5% diacetone alcohol and 50-55% water. The filaments are withdrawn from the bath after a travel of 8-10 inches and are led to a draw roller which rotates at a peripheral speed of about 50 metres per minute, so as to stretch the filaments continuously with their production. After stretching, the filaments may be dried and led to a winding, or winding and twisting device.

Example 2 A number of cellulose acetate threads proceeding in parallel formation from a creel of bobbins are passed over a guide and under a feed roller immersed in an aqueous bath containing 44-47% dioxane, and 3-5% methyl glycol monoacetate. The threads are fed in at aspeed of 5-7 metres per minute and after a travel through the bath of about 80-100 feet are withdrawn at a speed of 30-35 metres per minute by means of a draw roller, and thenpass to drying and winding apparatus. In this manner the threads may be stretched to 400-500% of their original length.

What I claim and desire to secure by Letters Patent is:

1. In a process for the treatment of formed artificial filaments, yarns, threads, ribbons, foils, films and like products comprising organic derivatives of cellulose, the steps of softening said materials 1 by the action of a liquid medium containing a non-solvent for the cellulose derivative and a high concentration of a volatile solvent therefor, in the presence of a low concentration of a less volatile solvent for the cellulose derivative having a lower vapor pressure than that of the non- 'solvent employed and subjecting the softened and a volatile solvent therefor in a concentration of at least 40%, in thepresence of from 1 to 10% of a less volatile solvent for the cellulose derivative having a lower vapor pressure than that of the non-solvent employed, and subjecting the softened material to a stretching operation applied in a plurality of stages.

3. In a process for the treatment of formed artificial filaments, yarns, threads, ribbons, foils, films and like products comprising organic derivatives of cellulose, the steps of softening saidmaterials by the action of an aqueous medium containing a volatile solvent for the cellulose derivative in a concentration of at least 40%, and from 1 to of a less volatile solvent therefor having a lower vapor pressure than that of water, and subjecting the softened material to a stretching operation.

4. In a process for the treatment of formed artificial filaments, yarns, threads, ribbons, foils, films and like products comprising organic derivatives of cellulose, the steps of softening said materials by the action of an aqueous medium containing a volatile solvent for the cellulose derivative in a concentration of at least 40%, and from 1 to 5% of a less volatile solvent therefor, subjecting the softened material to a stretching operation, and removing the softening medium from the material by drying, the less volatile solvent having, under the conditions of drying, a lower vapor pressure than that of water under those conditions.

5. In a process for the treatment of formed artificial filaments, yarns, threads, ribbons, foils, films and like products comprising cellulose acetate, the steps of softening said materials by the action of an aqueous medium containing a high concentration of a volatile-solvent for the cellulose acetate and a low concentration of a less volatile solvent such as methyl glycol mono-acetate, subjecting the softened material to a stretching operation, and removing the softening medium from the material by drying.

6. In a process for the treatment of formed artificial filaments, yarns, threads, ribbons, foils, films and like products comprising organic derivatives of cellulose, the steps of softening said materials by the action of an aqueous medium containing a high concentration of a solvent for the cellulose derivative having a vapor pressure greater than that of water and a low concentration of a less volatile solvent for the cellulose derivative having a lower vapor pressure than that of water, and subjecting the material to a stretching operation.

fl. In a process for the treatment of formed artificial filaments, yarns, threads, ribbons, foils,

films and like products containing cellulose acetate, the steps of softening said materials by the action of an aqueous medium containing a volatile solvent such as dioxane in a concentration of at least 40%, and from 1 to 5% of a less volatile solvent for the cellulose acetate, subjecting the material to a stretching operation and removing the softening medium from the material by drying, the less volatile solvent having, under the conditions of drying a lower vapor pressure than that of water under those conditions.

8. In a process for the treatment of formed artificial filaments, yarns, threads, ribbons, foils, films and like products containing cellulose acetate, the steps of softening said materials by the action of an aqueous medium containing from 40-47% dioxane and from 1-10% methyl glycol mono-acetate, subjecting the material to a stretching operation, and removing the softening medium from the material by drying.

9. In a process for the treatment of formed artificial filaments, yarns, threads, ribbons, foils, films and like products comprising cellulose acetate, the steps of softening said materials by the action of an aqueous medium containing a high concentration of a volatile solvent for the cellulose acetate and a low concentration of a less volatile solvent such as diacetone alcohol, subjecting the softened material to a stretching operation, and removing the softening medium from the material by drying.

10. In a processfor the treatment of formed artificial filaments, yarns, threads, ribbons, foils, films and like products containing cellulose ace tate, the steps of softening said materials by the action of an aqueous medium containing a volatile solvent such as acetone in a concentration of at least 40%, and from 1 to 5% of a less volatile solvent for the cellulose acetate, subjecting the material to a stretching operation and removing the softening medium from the material by drying, the less volatile solvent having, under the conditions of drying at lower vapor pressure than that of water under those conditions.

HENRY DREYF'US. 

